'Just a little cheap ten-year A-battery,' Himmel said. 'Costs another half cent.'

'And you built these carts?'

'Yes, Mr Ackerman.' Himmel took the cart from him and set it back on the floor; once more it wheeled industriously off. 'These are the ones too new to let go,' he explained. 'They have to practice.'

'And then,' Jonas said, 'you give them their freedom.'

That's right.' Himmel bobbed his large-domed, almost bald head, his horn-rimmed glasses sliding forward on his nose.

'Why?' Eric said.

Now the crux of the matter had been broached; Himmel turned red, twitched miserably, and yet displayed an obscure, defensive pride. 'Because,' he blurted, 'they deserve it.'

Jonas said, 'But the protoplasm's not alive; it died when the chemical fixing-spray was applied. You know that. From then on it – all of these – is nothing but an electronic circuit, as dead as – well, as a robant.'

With dignity Himmel answered, 'But I consider them alive, Mr Ackerman. And just because they're inferior and incapable of guiding a rocketship in deep space, that doesn't mean they have no right to live out their meager lives. I release them and they wheel around for, I expect, six years or possibly longer; that's enough. That gives them what they're entitled to.'

Turning to Eric, Jonas said, 'If the old man knew about this—'

'Mr Virgil Ackerman knows about this,' Himmel said at once. 'He approves of it.' He amended, 'Or rather, he lets me do it; he knows I'm reimbursing the company. And I build the carts at night, on my own time; I have an assembly line – naturally very primitive, but effective – in my conapt where I live.' He added, 'I work till around one o'clock every night.'